The GF Convection Parameterization: recent developments, extensions, and applications

We detail recent developments in the GF (Grell and Freitas, 2014, Freitas et al., 2018) convection parameterization and applications. The parameterization has been extended to a trimodal spectral size to simulate the interaction and transition from shallow, congestus and deep convection regimes. Another main new feature is the inclusion of a closure for non-equilibrium convection that resulted in a substantial gain of realism in the simulation of the diurnal cycle of convection, mainly associated with boundary layer forcing over the land. Additional changes include the transport of momentum, the use of three Probability Density Functions (PDF's) to describe the normalized vertical mass flux profiles from deep, congestus, and shallow plumes (respectively) in the grid box, and the option of using temporal and spatial correlations to stochastically perturb PDF's, momentum transport and the closures. Cloud water detrainment is proportional to mass detrainment and in-cloud hydrometeor mixing ratio, and transport of chemical constituents (including wet deposition) can be treated inside the GF scheme. Transport is handled in flux form and is mass conserving. Finally, the cloud microphysics has been extended to include the ice phase to simulate the conversion from liquid water to ice in updrafts with resulting additional heating release, and the melting from snow to rain within a user-specified melting vertical layer.

Gathering knowledge on mesopelagic ecosystems: insights from a parsimonious modelling approach

<p><span xml:lang="EN-US" data-contrast="none"><span>SEAPODYM-LMTL is the Lower (zooplankton) and Mid (micronekton) Trophic levels model of the Spatial Ecosystem </span></span><span xml:lang="EN-US" data-contrast="none"><span>And</span></span><span xml:lang="EN-US" data-contrast="none"><span> </span></span><span xml:lang="EN-US" data-contrast="none"><span>POpulation</span></span><span xml:lang="EN-US" data-contrast="none"><span> </span></span><span xml:lang="EN-US" data-contrast="none"><span>DYnamic</span></span><span xml:lang="EN-US" data-contrast="none"><span> Modeling framework. Currently, there is one zooplankton and 6 micronekton functional groups defined according to their vertical behavior and development times. The model is global and spatially explicit with transport described through a system of advection-diffusion equations. The vertical dimension is simplified into three layers -- epipelagic, upper and lower mesopelagic -- defined relatively to the euphotic depth. There are three vertically migrant and three non-migrant functional groups. The model is parsimonious with only a few parameters (6 for the zooplankton and 11 for the micronekton) that control the energy transfer efficiency from the primary production and the mortality and time of development that are linked to the water temperature. A data assimilation framework has been implemented to estimate those parameters.  We present briefly the latest results and future challenges of this model. They include the validation of vertical layer boundaries, the first zooplankton and micronekton parameters estimation using existing biomass observations, and the developments needed to use large global datasets of acoustic data.</span></span><span> </span></p>

Modeling diurnal variation of surface PM_2.5 concentrations over East China with WRF-Chem: impacts from boundary-layer mixing and anthropogenic emission

Diurnal variation of surface PM2.5 concentration (diurnal PM2.5) could dramatically affect aerosol radiative and health impacts and can also well reflect the physical and chemical mechanisms of air pollution formation and evolution. So far, diurnal PM2.5 and its modeling capability over East China have not been investigated and therefore are examined in this study. Based on the observations, the normalized diurnal amplitude of surface PM2.5 concentrations averaged over East China is weakest (∼1.2) in winter and reaches ∼1.5 in other seasons. The diurnal PM2.5 shows the peak concentration during the night in spring and fall and during the daytime in summer. The simulated diurnal PM2.5 with WRF-Chem and its contributions from multiple physical and chemical processes are examined in the four seasons. The simulated diurnal PM2.5 with WRF-Chem is primarily controlled by planetary boundary layer (PBL) mixing and emission variations and is significantly overestimated against the observation during the night. This modeling bias is likely primarily due to the inefficient PBL mixing of primary PM2.5 during the night. The simulated diurnal PM2.5 is sensitive to the PBL schemes and vertical-layer configurations with WRF-Chem. Besides the PBL height, the PBL mixing coefficient is also found to be the critical factor determining the PBL mixing of pollutants in WRF-Chem. With reasonable PBL height, the increase in the lower limit of the PBL mixing coefficient during the night can significantly reduce the modeling biases in diurnal PM2.5 and also the mean concentrations, particularly in the major cities of East China. It can also reduce the modeling sensitivity to the PBL vertical-layer configurations. The diurnal variation and injection height of anthropogenic emissions also play roles in simulating diurnal PM2.5, but the impact is relatively smaller than that from the PBL mixing. This study underscores that more efforts are needed to improve the boundary mixing process of pollutants in models with observations of PBL structure and mixing fluxes in addition to PBL height, in order to simulate reasonably the diurnal PM2.5 over East China. The diurnal variation and injection height of anthropogenic emissions must also be included to simulate the diurnal PM2.5 over East China.

ОСОБЕННОСТИ ПРИМЕНЕНИЯ АВТОНОМНОГО НЕОБИТАЕМОГО ПОДВОДНОГО АППАРАТА ПРИ ИЗУЧЕНИИ ПРОСТРАНСТВЕННОЙ СТРУКТУРЫ ГИДРОАКУСТИЧЕСКИХ ПОЛЕЙ

В работе описывается эксперимент, проведенный с участием автономного необитаемого подводного аппарата (АНПА), оснащенного высокоточной гидроакустической измерительной аппаратурой, низкочастотным гидроакустическим излучателем, а также береговыми лазерными деформографами. Целью данного эксперимента являлось изучение пространственновременного распределения поля давления, создаваемого низкочастотным гидроакустическим излучателем на шельфе клиновидной формы, а также выявление закономерностей трансформации гидроакустической энергии в сейсмическую. В ходе анализа и обработки полученных экспериментальных данных, была построена общая картина пространственного распределения поля гидроакустического давления на шельфе убывающей глубины, разработаны алгоритмы построения вертикальных разрезов поля давления по глубине на произвольном расстоянии от излучателя, по которым, в свою очередь можно вычислять горизонтальное распределение гидроакустической энергии на всем протяжении трассы излучения. По вертикальным распределениям давления, в представленной работе, были сделаны некоторые заключения о взаимодействии гидроакустического сигнала с дном и трансформации его в сейсмоакустический сигнал. Представлены результаты расчетов горизонтального распределения энергии и их сравнения с теоретически рассчитанными данными.The paper describes an experiment conducted with the participation an autonomous uninhabited underwater vehicle (AUV) was equipped with highprecision hydroacoustic measuring equipment, a lowfrequency hydroacoustic radiator, and coastal laser strainmeters. The aims of this experiment was to study the spatiotemporal distribution of the pressure field, created by a lowfrequency radiator on a wedgeshaped shelf, as well as to identify patterns of transformation of hydroacoustic energy into seismic. During the analysis and processing of the obtained experimental data, a general picture of the spatial distribution of the field of hydroacoustic pressure on the shelf of decreasing depth was gained, algorithms for constructing vertical layer of the pressure field by depth at an arbitrary distance from the radiator were developed, from which, in turn, it is possible to calculate the horizontal distribution of hydroacoustic energy all along the radiation path. By the vertical pressure distributions, in the present work, some conclusions were inferred about the interaction of the hydroacoustic signal with the bottom and its transformation into a seismic signal. The results of calculations of the horizontal energy distribution and their comparison with theoretically calculated data are presented.

Modeling diurnal variation of surface PM_2.5 concentration over East China with WRF-Chem: Impacts from boundary layer mixing and anthropogenic emission

Diurnal variation of surface PM2.5 concentration (diurnal PM2.5) could dramatically affect aerosol radiative and healthy impact, and can also well reflect the physical and chemical mechanisms of air pollution formation and evolution. So far, diurnal PM2.5 and its modeling capability over East China have not been investigated, and therefore, are examined in this study. Based on the observations, the normalized diurnal amplitude of surface PM2.5 concentrations averaged over East China is the weakest (~1.2) in winter, and reaches ~1.5 in other seasons. The diurnal PM2.5 shows the peak concentration during the night in spring and fall and during the daytime in summer. The simulated diurnal PM2.5 with WRF-Chem and its contributions from multiple physical and chemical processes are examined in the four seasons. The simulated diurnal PM2.5 with WRF-Chem is primarily controlled by planetary boundary layer (PBL) mixing and emission variations, and significantly overestimates the observations during the night. This modeling bias is likely primarily due to the inefficient PBL mixing of primary PM2.5 during the night. The simulated diurnal PM2.5 is sensitive to the PBL schemes and vertical layer configurations with WRF-Chem. The PBL mixing coefficient instead of PBL height is found as the critical factor determining the PBL mixing of pollutants in WRF-Chem. The increase of lower limit of PBL mixing coefficient during the night can significantly reduce the modeling biases in diurnal PM2.5 and also the mean concentrations, particularly at the major cities of East China. It can also reduce the modeling sensitivity to the PBL vertical layer configurations. The diurnal variation and injection height of anthropogenic emissions also play roles on simulating diurnal PM2.5, but the impact is relatively smaller than that from the PBL mixing. This study underscores that more efforts are needed to improve the boundary mixing process of pollutants in models with observations of PBL structure and mixing fluxes in addition to PBL height, in order to simulate reasonably the diurnal PM2.5 over East China. The diurnal variation and injection height of anthropogenic emissions are also necessary to be included to simulate the diurnal PM2.5 over East China.